NEW: Blast hits Foreign Ministry in Benghazi

Security officials say a powerful explosion has caused serious damage to Libya's Foreign Ministry building in the heart of the coastal city of Benghazi.

The early Wednesday morning blast also damaged the building next door housing the Benghazi branch of the Libyan Central Bank.

The officials said several passers-by were slightly injured by the blast, which blew out windows in nearby buildings. The officials spoke on condition of anonymity because they were not authorized to speak to the media.

The blast came exactly one year after al-Qaida-linked militants stormed the U.S. Consulate in the eastern city of Benghazi, killing the U.S. ambassador and three other Americans. Both Wednesday's bombing and last year's attack on the American consulate took place on the anniversary of the Sept. 11, 2001, attacks.